One of the methods for disinfecting environments contaminated with viruses and bacteria is the use of UVC light to disinfect high-risk surfaces. When this radiation strikes contaminated surfaces, it destroys the DNA and RNA of bacteria, viruses, fungi, and other pathogens, thereby disinfecting the environment. The approved major applications of this method include disinfection of hospital rooms, clinics, medical offices, laboratories, healthcare centers, as well as public places such as kindergartens, schools, government offices, religious sites, mosques, Hosseiniyas, and other facilities with high visitor traffic. This application has been emphasized in the guidelines of Iranian universities of medical sciences.
UVC lamps disinfect the environment and air by creating two factors:
A) UVC Radiation:
After 30 minutes, they complete the disinfection of irradiated surfaces by up to 99%. Therefore, the environment should be as dark as possible, and movement without protective covering is prohibited in the environment. For disinfection of indoor spaces, all cabinet doors, glass shelves, and items in the room should be left open. (Glass blocks the passage of this radiation.)
B) Ozone Gas:
When UVC radiation interacts with ambient oxygen, some O₂ is converted into O₃ (ozone), which is a highly oxidizing and unstable gas. It destroys pathogens by damaging their outer shell and then reverts to oxygen after 20 to 60 minutes. Thus, the ambient air and surfaces not directly irradiated are disinfected in this manner. Therefore, before turning on the lamp, turn off the ventilation fan, close the room door, and seal any gaps around the door as much as possible.
Practical Tips:
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When UVC lamps are on, you must not look at the light, nor should the radiation come into contact with you. Therefore, the on/off switch should be located outside the room and preferably activated after working hours. If direct exposure is unavoidable, individuals should use protective clothing and goggles.
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The effect of the generated ozone gas lasts between 20 minutes and one hour after the lamp is turned off. Therefore, during this period, care must be taken not to inhale ozone. (It should be noted that ozone gas has a sharp, unpleasant odor — this gives us an indicator: if we no longer smell this odor in the environment, the ozone has converted back to oxygen.) If you need to re-enter the space quickly, open the windows and use a ventilation fan 20 minutes after turning off the lamp.
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Periodically cleaning the lamp surface with an alcohol-moistened cloth improves radiation performance.
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Cleaning the environment before turning on the lamp significantly improves disinfection performance.
